The Alteration in the Center of Pressure and Duration Ratio of Stance Sub-Phases during Upslope Walking

초록

Upslope-walking is more challenging and therefore has a greater fall risk than level-walking. The current study aimed to investigate the difference in control strategy for stability between level and upslope walking using the center of pressure (COP) and the ratio of three sub-phases in stance phase (loading-response, mid-stance and push-off). Two hypotheses were tested: the excursion, range, and speed of the COP increases in the mediolateral and anteroposterior directions with slope grade; and the duration of the midstance phase increases with slope grade. Eleven male subjects walked on a level (0A degrees) surface and upslope at 15A degrees and 25A degrees. The duration of the mid-stance phase was significantly greater in the 25A degrees upslope-walking condition than that in the level and 15A degrees upslope-walking conditions (both p < 0.05). This result implies that the subjects adopted a different control strategy when walking upslope at 25A degrees than when walking level and upslope at 15A degrees. The range and speed of the mediolateral COP were larger in the 25A degrees upslope-walking condition than those in the level and 15A degrees upslope-walking conditions (p < 0.05). This result indicates that a change in control strategy during upslope-walking at 25A degrees can improve mediolateral stability. These findings imply that a transition grade exists between 15A degrees and 25A degrees where one can alter their control strategy to improve stability during upslope-walking.

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